Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Cash flows from operating activities:
Net (loss) income	$ (34,959)	$ 66,112
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation	85,194	79,264
Amortization of intangible assets	25,589	11,247
Non-cash stock-based compensation expense	6,336	5,528
Provision for (benefit from) deferred income taxes	1,647	(19,838)
Equity in earnings of unconsolidated affiliates, net	(6,777)	(7,346)
Gains on sales of assets, net	(2,568)	(1,965)
Non-cash interest expense, net	854	783
Other non-cash items, net	(926)	(5,578)
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	121,646	(61,993)
Contract assets	(104,490)	26,799
Inventories	(8,980)	651
Other assets, current and long-term portion	36,268	(7,961)
Accounts payable and accrued expenses	14,537	153,386
Contract liabilities	(13,802)	14,782
Other liabilities, current and long-term portion	11,949	3,293
Net cash provided by operating activities	131,518	257,164
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(21,840)	(88,646)
Capital expenditures	(83,191)	(48,058)
Proceeds from sale of property and equipment	4,630	6,035
Payments for other investments	(960)	(4,350)
Proceeds from other investments	0	557
Other investing activities, net	0	(150)
Net cash used in investing activities	(101,361)	(134,612)
Cash flows from financing activities:
Proceeds from credit facilities	773,500	18,155
Repayments of credit facilities	(855,083)	(8,869)
Payments of finance lease obligations	(41,600)	(38,222)
Payments for stock-based awards	(3,996)	(3,753)
Repurchases of common stock	(13,791)	0
Other financing activities, net	(17,046)	(502)
Net cash used in financing activities	(158,016)	(33,191)
Effect of currency translation on cash	256	(72)
Net (decrease) increase in cash and cash equivalents	(127,603)	89,289
Cash and cash equivalents - beginning of period	360,736	423,118	$ 423,118
Cash and cash equivalents - end of period	233,133	512,407	$ 360,736
Supplemental cash flow information:
Interest paid	23,178	21,689
Supplemental disclosure of non-cash information:
Additions to property and equipment from finance leases	$ 48,604	$ 50,772